Clock Source; External Clock Source (Compulsory); Schematic For The External Flash And Ram (Psram) - Espressif Systems ESP32-C6 Series Hardware Design Manuallines

2 Schematic Checklist
R17 0
GND
C10
0.1uF
30
U0RXD
29
U0TXD
28
VDDPST2
27
GPIO15
26
SPID
25
SPICLK
24
SPIHD
23
VDD_SPI
22
SPIWP
21
SPIQ
C16
0.1uF
ESP32-C6
GND
Figure 6: Schematic for the External Flash and RAM (PSRAM)

2.4 Clock Source

ESP32-C6 has two clock sources:
• External clock source
• RTC clock source
3

2.4.1 External Clock Source (compulsory)

Currently, the ESP32-C6 firmware only supports 40 MHz crystal.
Crystal
The circuit for the crystal is shown in Figure 7. The initial values of external capacitors C1 and C4 can be
determined according to the formula:
where the value of C (Load Capacitance) can be found in the crystal's datasheet, and the value of C
L
to the PCB's stray capacitance. The values of C1 and C4 need to be further adjusted after an overall test.
In order to reduce the impact of high-frequency crystal harmonics on RF performance, please add a series
component (resistor or inductor) on the XTAL_P clock trace. Initially it is suggested to use an inductor of 24 nH,
and the value should be adjusted after an overall test. Note that the accuracy of the selected crystal should be
within ±10 ppm.
Espressif Systems
GPIO22
GPIO21
GPIO20
GPIO19
GPIO18
VDD33
U0RXD
R3 499 U0TXD
GPIO15
R16 0 SPID
R15 0 SPICLK
R14 0 SPIHD
R13 0 SPIWP
R10 0 SPIQ
C17
VDD_SPI
1uF
GND
C1 × C4
C =
L
C1 + C4
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R8
10K(NC)
SPICS0 1
/CS
SPICLK 6
CLK
SPIHD 7
/HOLD
U2
2
+ C
stray
11
ESP32-C6 Series Hardware Design Guidelines v1.0
VDD_SPI
5 SPID
DI
2 SPIQ
DO
3 SPIWP
/WP
FLASH
NC: No component.
GND
1
stray
C
B
A
refers